• Journal of the Korea Organic Resources Recycling Association
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• v.2 no.1
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• pp.87-98
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• 1994

Sludge minimization in an water treatment plant can be achieved by optimizing a main water treatment process as well as by enhancing a thickening and a dewatering facilities. In this study, dewatering and drying techniques for reducing the quantity of the water sludge generated from the conventional water treatment plant in the local states were investigated by reducing its water content. Not only the types and dosages of polymers but also the mixing intensity of the mixtures of a concentrated sludge and polymers on the different pH were evaluated for the optimum dewatering conditions of the water sludge. Weight reduction of the water sludge was also tested at a given temperature range. The dewatering efficiency of the water sludge was not affected by the types of polymer but by mixing intensity(GT value) in this study. pH effect on dewaterbility of the water sludge took a major role at the neutral pH range. The optimal polymer dose was 1.5 mg-polymer/g-TSS(about 40mg/L as polymer). Dewaterability was enhanced at a lower mixing intensity(GTbelow 10,000 sec-1). Free water in the void of sludge cake was dried around $100^{\circ}C$, chemical bound water was evaporated around $320^{\circ}C$, and organic material was burned out at the range of 300 to $600^{\circ}C$. Ignition losses of the water sludge were varied 15 to 40 % as the raw water quality. The ignition loss due to the chemical bound water was 10-20% and the loss due to the organic material was 4-20% of the total ignition loss.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.9
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• pp.894-899
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• 2010

We coordinated the experiments with ozone pretreatment and two-phase anaerobic digestion using solid-liquid separation to raise the efficiency of sludge volume reduction and obtained the following results. The pre-treatment with ozone reduced the solid concentration in the average of TSS $8.3{\pm}2.0%$ TSS and $9.2{\pm}}2.8%$ VSS. Of the organic material, TCOD decreased $5.1{\pm}2.4%$, but SCOD showed $72{\pm}6.5%$ increased, which was due to destruction of the cell wall and dissolution of icell media by the powerful oxidative stress of ozone. During the two-phase anaerobic digestion process, we achieved the reduction of $21.5{\pm}3.4%$ TSS, $20.2{\pm}8.4%$ VSS, $32.1{\pm}7.9%$ TCOD and $22.1{\pm}7.2%$ SCOD in average. The maximum methane gas production were 177.6 mL per g TSS, 210.8 mL per g VSS, 127.0 mL per g TCOD and 1452.0 mL per g SCOD, respectively. Solid material reduction through the two-phase anaerobic digestion and MLE (Modified Ludzack-Ettinger) processes were 93.8% of TSS and 92.0% of VSS. We concluded that suggested two-phase anaerobic digestion and MLE process could achieve the reasonable production of biogas and a maximum reduction of the sludge volume.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.1
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• pp.90-99
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• 2005

This study was conducted to survey the attitude of Chuncheon citizens on food waste generation. About 50% of the citizens were generating $5{\sim}10{\ell}$ of MSW (municipal solid wastes) a week. These answers were almost from below 35 years old. And the citizens answered that the ratio of FW (food waste) to MSW were 10-30%. They were generating FW enveloped in a standardized vinyl bag after dewatering. About 10% of the answers were generating FW with MSW without any dewatering. The reason for FW generation in large quantities was to cook and buy much more food materials than needed. They thought that malodor and harmful insect were the most severe problems from FW storage. The systematic management was the most needed in individual restaurants. They answered that an individual citizen should make an effort to reduce FW generation. However, in fact, they did not do their best to try to reduce FW generation. They agreed that an individual citizen should try to reform 'present food culture' and to think FW as resources.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.1
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• pp.12-21
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• 1999

This study was carried out to improve the cultivation method of paddy rice when the application amount of nitrogen decreased. We investigated the growth and the yield of paddy rice, the changes of nutrients in the soil solution, soil and paddy rice. The results are as follows. The yield at the N4 plot(N $73kg\;ha^{-1}$) was higher than that of control(N $110kg\;ha^{-1}$). N1(N $55kg\;ha^{-1}$), N2(N $55kg\;ha^{-1}$), and N3(N $73kg\;ha^{-1}$). The number of panicle per square meter at the N4 plot was larger than that of control plot. The increase in yield at the N4 plot was due to increased number of panicle where planting density was two times higher compared to the control plot. The availability of nitrogen at the N4 plot also was two times higher than that of control plot. The pH in soil solution was around 7 and did not change largely. The $K^+$ concentration in soil solution at all plots decreased gradually. The $Ca^{2+}$ concentration in soil solutions increased gradually, and decreased at the later stage slightly. The P concentration in soil solution decreased gradually, increased after the heading stage, and then decreased due to decrease of soil temperature. Leaching of $Ca^{2+}$ was higher, while that of $K^+$ and P was lower compared to other ions. Total content of nutrients in soil after harvest decreased. Contents of total N, total P, and O.M. at the N4 plot were higher than those of the other plots. The content of total N and O.M. was correlated to yield. Contents of N, P and K in rice straw and grain at the N4 plot were the highest among all plots. In conclusion, to decrease N application amount in paddy rice cultivation as well as to maintain yield, planting density should be twice of control and the amount of application of N fertilizer should be two-third of control where N fertilizer should be applied mainly at 20 and 10 day before heading.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.54-59
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• 2011

This test established the bioavailability and sample input by mixing the maintaining the microbial machine parts and food waste leachates in weight of 2:1 as advanced experiment, maintaining the constant temperature, agitating and observing its weight and property change for 60 hours. And, I injected daily the established microbial machine parts and food waste leachates rate, maintained the temperature in the reactor with $55{\sim}65^{\circ}C$, and agitated with constant speed. I studied the recycling possibility of food waste leachates by extracting the sample after 24 hours, verifying its characteristics, and repeating the food waste leachates input and sample extraction for about 40 days. Considering all about the results of this study, I saw that 87.32% of food waste leachates was reduced, and the solid of bluebug or food included in the food waste leachates was decomposed within 24 hrs. pH for 43 days after 9 days of stabilization period was maintained from 3.7~3.9 and the ignition loss from 88.67~87.3%, and the quantity of organic matter from 77.6~80.88%. With the similar result daily maintained, it is considered to progress more the minimization by inputting the future food waste leachates. C/N rate satisfies the less than 25 that is the composting basis within 8 days, maintaining between 13~15, with 2% of salt not exceeded, it is able to recycle as the compost of food waste leachates as based on the composting with no extracted heavy metal content.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.500-500
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• 2016

전국의 농업용 저수지 중 장기간 높은 유기물 및 영양염의 농도로 인해 부영양화가 우려되는 71개 저수지에 대하여 수질오염 및 퇴적물오염 특성을 분석하였다. 수질오염 특성 분석 결과, 평균농도가 COD 11.7 mg/L, TOC 6.8 mg/L, TN 1.844 mg/L, TP 0.101 mg/L, SS 18.1 mg/L, Chl-a 57.3 mg/$m^3$ 로 분석되었다. 조사 대상 저수지 71개 지구 중 COD 46.3 %, TN 84.4 %, Chl-a 63.7 %가 농업용수 수질기준 초과 저수지로 조사되었다. 또한 연구 대상지구의 주요 오염원으로 생활계오염원 31개 저수지의 COD 11.1 mg/L이며, 축산계오염원 40개 저수지의 COD 12.2 mg/L로 나타났다. 각 항목의 수질 결과에 대한 평균 오염도를 분석한 결과, 축산계 오염원이 생활계 오염원 저수지보다 부유물질(SS)을 제외하고 모든 항목에서 오염도가 높게 나타났다. 그러나 TN, TP는 오염원에 따라 크게 차이를 보이지는 않았으며, 축산계 오염원 저수지의 수질 오염도는 모든 항목에서 농업용수 수질기준을 초과하였다. 장기적인 수질오염 저수지에 대하여 퇴적물의 오염 특성을 조사하였으며, 퇴적물오염으로 인한 수질오염 영향관계를 조사 분석하였다. 퇴적물 오염 특성 분석 결과, 강열감량 10.5 %, 총질소 3,480 mg/kg, 총인 1,299 mg/kg으로 오염 수준이 전체적으로 높게 조사되었다. 생활계오염원 31개 저수지의 강열감량 9.8 %, 총질소 2,711 mg/kg, 총인 1,178 mg/kg이며, 축산계오염원 40개 저수지의 강열감량 11.1 %, 총질소 4,076 mg/kg, 총인 1,393 mg/kg로 나타났다. 수질 중 COD, TOC, TN, TP, SS, Chl-a의 오염도와 퇴적물중 강열감량, 총질소, 총인의 각 항목간 상관관계를 분석한 결과, 퇴적물 내 다른 항목에 비해 SS를 제외하고 총인이 모든 수질 항목과 정(+)의 상관관계를 나타내었다. 특히 퇴적물 중 총인과 수질의 TP가 가장 높은 상관성을 나타내는 것으로 조사되었는데, 이는 퇴적물 내 총인이 수질오염에 가장 많은 영향을 줄 수 있으며, 상호작용이 있음을 의미한다고 하겠다. 또한 수질의 TP 오염도에 따라 부영양화 및 조류의 활성화가 크게 영향을 받는다는 기존의 연구결과에 의하면 퇴적물 내 총인의 오염도가 부영양화와 조류 번식에 영향을 크게 미칠 것이라 판단된다.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.5-13
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• 2022

The current environmental problem is that environmental pollution is accelerating due to the generation of large amounts of waste and indiscriminate consumption of energy. Fossil fuels, a representative energy production fuel, are burned in the process of producing energy, generating a large amount of greenhouse gases and eventually causing climate change. In addition, the amount of waste generated worldwide is continuously increasing, and environmental pollution is occurring in the process of waste treatment. One of the methods for simultaneously solving these problems is the energy recovery from and reduction of organic wastes. Sewage sludge generated in sewage treatment plants has been treated in various ways since ocean disposal was completely prohibited, but the amount generated has been continuously increasing. Since the sewage sludge contains a large amount of organic materials, it is desirable to recover energy from the sewage sludge and reduce the final discharged waste through anaerobic digestion. However, most of the excess sludge is a mass of microorganisms used in sewage treatment, and in order for the excess sludge to be anaerobically digested, the cell walls of the microorganisms must be destroyed first, but it takes a lot of time to destroy the cell walls, so high rates of biogas production and waste reduction cannot be achieved only by anaerobic digestion. Therefore, the pre-treatment process of solubilizing excess sludge is required, and the thermal solubilization process is verified to be the most efficient among various solubilization methods, and high rates of biogas production and waste reduction can be achieved by anaerobic digestion after destroying cell walls the thermal solubilization process. In this study, when pretreating TS 10% thickened excess sludge through a thermal solubilization system, a study was conducted on solubilization characteristics according to retention time and operating temperature variables. The experimental variables for the retention time of the thermal solubilization system were 30 minutes, 60 minutes, 90 minutes, and 120 minutes, respectively, while the operating temperature was fixed at 160℃. The soulbilization rates calculated through TCOD and SCOD derived from the experimental results increased in the order of 12.11%, 20.52%, 28.62%, and 31.40%, respectively. And the variables according to operating temperature were 120℃, 140℃, 160℃, 180℃, and 200℃, respectively, while the operating retention time was fixed at 60 minutes. And the solubilization rates increased in the order of 7.14%, 14.52%, 20.52%, 40.72%, and 57.85%, respectively. In addition, TS, VS, T-N, T-P, NH₄⁺-N, and VFAs were analyzed to evaluate thermal solubilization characteristics of thickened excess sludge. As a result, in order to obtain 30% or more solubilization rate through thermal solubilization of TS 10% thickened excess sludge, 120 minutes of retention time is required when the operating temperature is fixed to 160℃, and 170℃ or more of operating temperature is needed when the operating time is fixed to 60 minutes.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.1
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• pp.75-83
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• 2004

Temperature-phased anaerobic digestion (TPAD), anaerobic sequencing batch reactor (ASBR), and co-digestion technologies were combined together in order to overcome low efficiencies of conventional anaerobic sewage sludge digestion processes. In the performance, TPAD-ASBR process showed high VS removal efficiency over 60% up to the organic loading rate (OLR) of 2.7 g VS/L/d. The first-stage of TPAD-ASBR and control system played a most significant role in VS destruction and methane production. Methane production rate (0.79 l $CH_4/L/d$) of the system was higher than that (0.59 l $CH_4/L/d$) of the control system. The substrate characteristics of the sewage sludge, such as low VS concentration (1.5%, w/w) and biodegradability, were properly improved by the addition of food waste as a co-substrate, leading to more efficient VS removal and methane production. With several track studies, it was revealed that the independent solid retention time (SRT) of those systems prevented untreated particles from outflowing and also, extended the retention time of the active biomass for further degradation. Consequently, it was confirmed that the sequencing batch operation of the TPAD process using co-substrate was a promising alternative for the recycling of sewage sludge with low VS content.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.392-402
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• 2020

We investigated the concentrations of acid volatile sulfide (AVS), ignition loss (IL), total organic carbon (TOC), total nitrogen (TN), and metallic elements (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, and Zn), in August 2015, to determine the spatial distribution and pollution status of organic matter and metals in the surface sediment of Jinju Bay, a spraying shellfish farming area, Korea. The concentrations of organic matter and metallic elements were significantly higher in the southern part of the bay than in the mouth and center of the bay. The C/N ratio (5.7~8.0) in the sediment represents the dominance of organic matter of oceanic origin in the surface sediment of the study area. The concentrations of AVS, TOC, and metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) were much lower than the values of the sediment quality guidelines applied in Korea. Based on the results of the pollution load index (PLI) and ecological risk index (ERI), the metal concentrations in the surface sediment of Jinju Bay have a weakly negative ecological effect on benthic organisms although the sediments with high metal pollution status are distributed in the southern parts of the bay, with high dense shellfish farming areas. Thus, the surface sediments in Jinju Bay are not polluted with organic matter and are slightly polluted with metallic elements.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.1
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• pp.83-98
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• 1996

Recently, signigicant interest is given to the recycling of glass bottles. This is because the importance of glass bottle recycling is growing in terms of resource conservation and waste minimization. In this paper, authors analyzed the present situation and problems in glass bottle recycling, summarized the recycling activity in foreign countries and suggested legal and institutional strategies based upon citizen's attitude survey to improve glass bottle recycling activity